new simple downscaling ideas

cmd/playground/mask/mask.go

@@ -0,0 +1,62 @@
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/draw"
+	"image/png"
+	"os"
+)
+
+type XORMask struct {
+	dst, src image.Image
+}
+
+func (m XORMask) ColorModel() color.Model { return color.Gray16Model }
+func (m XORMask) Bounds() image.Rectangle { return m.dst.Bounds() }
+func (m XORMask) At(x, y int) color.Color {
+	srcColor := m.src.At(x, y)
+	dstColor := m.dst.At(x, y)
+
+	if ((dstColor == color.Black) || (srcColor == color.Black)) &&
+		!((dstColor == color.Black) && (srcColor == color.Black)) {
+		return color.Black
+	}
+	return color.White
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	if err != nil {
+		panic(err)
+	}
+
+	grayImg := image.NewGray16(img.Bounds())
+	for y := img.Bounds().Min.Y; y < img.Bounds().Max.Y; y++ {
+		for x := img.Bounds().Min.X; x < img.Bounds().Max.X; x++ {
+			c := img.At(x, y)
+			grayImg.Set(x, y, color.Gray16Model.Convert(c))
+		}
+	}
+	canvas := image.NewRGBA(img.Bounds())
+	circle := Circles(canvas.Bounds(), canvas.Bounds().Dy()/6)
+	for i := 0; i < 24; i++ {
+		c := <-circle
+		draw.Draw(canvas, c.Bounds(), xor{c, canvas}, c.Bounds().Min, draw.Src)
+	}
+
+	err = png.Encode(
+		os.Stdout, XORMask{
+			grayImg,
+			BlackAndWhite{
+				Exchange{
+					canvas,
+				},
+			},
+		},
+	)
+	if err != nil {
+		panic(err)
+	}
+
+}